Gas sensor

According to one embodiment, the gas sensor includes a porous plate-like sintered body comprising trisilicon tetranitride needle crystals; two first catalyst metal thin films and one second catalyst metal thin film, formed on one surface of the plate-like sintered body in a non-contacted state with each other; oxygen ion-conductive solid electrolyte thin films formed on the respective surface; a surface layer thin film formed on the respective surfaces, so that a first measurement part, a second measurement part and a third measurement part are constituted; and a glass sealing layer comprising silicon oxide, formed on other surface of the porous plate-like sintered body, a surface other than the surface of the porous plate-like sintered body having the first catalyst metal thin film and the second catalyst metal thin film formed thereon, and a side of the first measurement part and the second measurement part.